Firebug Coding Style

From FirebugWiki

This document attempts to explain the basic styles and patterns, that are used in the Firebug codebase. New code should try to conform to these standards, so that it is as easy to maintain as existing code. Of course every rule has an exception, but it's important to know the rules nonetheless!

The incrementation and decrementation operators are not separated by spaces. So e.g. you should write while(i-- > 0) instead of while(i --> 0) to avoid misinterpretations.

Source File Size

A source file should avoid huge amount of code lines. Couple thousands of lines in a file is already a lot. Firebug is using AMD syntax and more smaller files (modules) is preferred.

Line Length

100 characters or less. There is no exception in *.js files! In some cases this rule can be broken in *.html or *.xul files. But keep in mind long lines are hard to read (also search results are hard to read).

When wrapping lines, operators stay at the end of a line.

if((... &&
...)||
...){}

var string = ... +
...;

Also member operators stay at the end of the line.

var service = Cc[...].
getService(...);

Indentation

Four spaces per logic level.

Commands

Every command must end with a semicolon and must be on its own line.

var foo =1;var bar =2;
foo = someFunction();
bar +=3;return bar;

License

Files should include a license note at the first line of the file:

/* See license.txt for terms of usage */
...

In case of *.xml files (e.g. in overlays), this must be after XML declaration, for example:

<?xmlversion="1.0"?><!-- See license.txt for terms of usage -->
...
</xml>

In case of *.properties or *.manifest files, this must be commented using # character.

# See license.txt for terms of usage
...

Control Structures

Existing Firebug codebase uses braces on the next line like as follows:

function foo(){// ...}

Yes, there can be exceptions and K&R style can be preferred in some cases. For example, definition of a config object.

Firebug codebase also uses the following horizontal separator for dividing members of one object (this separator uses indentation (4 spaces) since it's used within an object scope that is indented (100 characters long).

Naming

American English is used for all labels and comments. That means, that you should write e.g. synchronize instead of synchronise or color instead of colour.

Functions and Methods

Functions should use camelCase but should not capitalize the first letter. Also functions names must start with a verb.

function initialize(){}

function getLocationList(){}

Objects

Constructors for objects should be capitalized and use CamelCase.

function ObjectConstructor(){}

Firebug.MyModule= extend(Firebug.Module,{});

MyObject.prototype=(){
myMethod:function(){}};

Constants

Constants should be capitalized as follows:

var MY_CONSTANT =true;

Use var instead of const, since the code can also be used in the browser environment where const is not supported.

Variables

Variables should use camelCase and not capitalize the first letter. Variable definitions should be done separately, not comma-separated.
If abbreviations are used, they should be written lower case at the beginning of a variable but in capitals when they are in the middle of the name.